The truth.
Hitler was shot in the head by sniper fire as him and a few of his loyal men were fighting as a last stand. His body was found in rubble by Russian soldiers outside of the bunker entrance.
Russians soldiers rushed into the bunker fighting off two of the last Nazi guards before shooting all the women and children in the bunker.
Allied forces did not tell the official reports for fear it would shine a dark light on allied forces and fear of revolts since many still in power supported Hitler even after the downfall.
So they made up the suicide report.
Anyone who took cyanide wouldn't be able to hold a hand gun let alone shoot themselves in the back of the head.
